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Description

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Causes

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Moldy Corn Poisoning or Leukoencephalomalacia in Horses

Description It has been long recognized that a toxin forms in poorly stored corn that causes a serious disease of the brain in horses, leukoencephalomalacia. The toxin fumonisin B1 has been identified as the cause. The toxin is produced by the fungus Fusarium moniliforme. Minute quantities of the toxin cause serious disease so frequently the feed appears normal. LEM has a history of coming in outbreaks when the weather has been wet.

Additional information

A disease of the white matter of the cerebral cortex resulting from the ingestion of corn or corn stalks which are contaminated with Fusarium moniliforme which produces the toxic compound. Mold may also contaminate pelleted rations which combine grain and roughage.

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Signs

AnamnesisClinical Signs

1. Only seen in equidae.

2. Signs are identical to viral encephalitides.

3. Severe icterus may be present either from anorexia, or liver damage from other aflatoxins contaminating the food.

Etiology 1. Intoxication caused by the ingestion of moldy fodder. 2. Corn incubated with grains of toxic corn usually grows Fusarium and, in turn, becomes toxic. 3. As little as 10 pounds of infected corn over 12 days of feeding has caused encephalitis in mules. 4. The toxin production seems to occur best around 0 degrees C. 5. Other aflatoxins which are elaborated by Fusarium spp can cause hepatitis and skin necrosis. 6. If aflatoxin assays are greater than 200 parts/billion, then the feed has significant contamination.

FumonisinB

DiagnosisDIAGNOSIS

Any rapidly progressive disease of the brain in horses fed corn should be suspect for LEM. Though definitive diagnosis can only be made by finding the characteristic changes in the brain at necropsy some other changes are helpful. Fumonisin is liver toxic so also signs of liver disease may be evident. These include elevated serum AST, GGT, alkaline phosphatase and total bilirubin. There are changes in the CSF fluid also including inflammatory cellular populations in CSF, and a possible elevation in myelin basic protein in CSF.